Both Kellan Lutz and Nikki Reed talked in recent interviews about a special scene at the end of Breaking Dawn 2. Somehow in the vast game of telephone that interviews can become this information morphed into a spoof, dance-off, prank on Bill Condon that the actors did would be tacked onto the end of the film.
Summit clarified the following to EW
Nikki Reed speculated to Perez Hilton that she thought the end could be a dance that 150 members of the cast performed one day on set as a surprise to Condon. But not so fast! Summit has confirmed to EW that this dance scene (which does indeed exist) is not in the final cut of the film. For now, the mystery continues…